This retrospective matched cohort study tested the hypothesis that an incomplete periacetabular acetabuloplasty, as an added step to delayed open reduction, diminishes the risk of developing acetabular dysplasia.

29 hips from 23 patients with idiopathic DDH that underwent intentionally delayed open reduction and acetabuloplasty at our institution from 2003 to 2010 were matched for age at presentation and bilaterality to historic controls. These were 29 hips from 26 patients, treated with open reduction alone from 1989 to 2003. Residual dysplasia treated with pelvic osteotomy, AVN grade II-IV, and rate of re-intervention were the outcome measures.

The mean ages at diagnosis and at surgery were 8.62 weeks and 12.97 months, respectively. At latest follow-up, 27 hips in the acetabuloplasty group and 22 in the open reduction alone group had satisfactory radiographic outcome (Severin class Ia, Ib or II) (p=0.16). 18 of the 58 hips (31.0%) had AVN, 7 (24.14%) in the case group and 11(37.93%) in the control group. Further surgery was required in 15 of the 29 hips in the open reduction alone group. These included 2 revision of open reductions, 5 pelvic osteotomies, 3 varus derotation osteotomies, and 5 apo or epiphysiodesis whilst only one patient in the acetabuloplasty group required a medial screw epiphysiodesis for late lateral growth arrest. There is a positive association between the need for further surgery and open reductions alone: the odds ratio is 14.00 and the 95% confidence interval (1.97, 99.63), p=0.0017. The five hips in the open reduction alone group that required a pelvic osteotomy were intervened at an average of 31.45 (±9.07) months.

The addition of an incomplete periacetabular periacetabuloplasty to all hips undergoing open reduction eliminated residual acetabular dysplasia in this cohort whilst it does not appear to have deleterious effects, as evidenced by the similar Severin and McKay scores.